The wearable demand of modern electronic devices makes flexible and stretchable energy storage device urgently needed.Stretchable and flexible supercapacitors(SCs)are energy storage devices that provide ultrahigh power density while having long-term durability,high security,and electrochemical stability.Among different SCs electrode materials,CNTs and graphene-based materials exhibit great potential in terms of stretchable SCs due to its ultrahigh electrical conductivity,large specific surface area and good mechanical properties.In this review,the state-of-the-art process and achievements in the field of stretchable SCs enabled by CNTs and graphene are presented,which include the novel design strategy,mechanical and electrochemical properties.The final section highlights current challenges and future perspectives on research in this thriving field.
Exploring advanced electromagnetic wave(EMW)absorbers is one of the most feasible ways to solve the increasing electromagnetic pollution in both military and civil fields.In this work,γ-graphyne(γ-GY)is synthesized by a mechanochemical route using CaC2 and hexabromobenzene(PhBr6).Then three-dimensional(3D)reduced graphene oxide/γ-GY(RGO/GY)heterostructures are prepared through facile solvothermal self-assembly and subsequent thermal reduction.The influences of calcination temperature and the content ofγ-GY of the composite on EMW absorption performance are fully investigated.The minimum reflection loss(RL)value of the RGO/GY composite foam is−71.73 dB at 10.48 GHz with the matching thickness of 3.54 mm,and the effective absorption bandwidth(EAB)less than−10 dB is 7.36 GHz.Moreover,excellent terahertz(THz)absorption property is also obtained at 0.2–1.6 THz.The RL of 84.08 dB is acquired,and the EAB covers 100%of the entire measured bandwidth.In addition,the composite is also a promising anticorrosive EMW absorber.This work provides encouraging findings,which are also instructive for the potential advantages of graphyne-based materials as highly efficient EMW absorbers in both gigahertz and terahertz band ranges.
p-Phenylenediamine(PPD)functionalized graphene oxide(GO)materials(PPDG)were prepared through a one-step solvothermal process and their application as supercapacitors(SCs)were studied.The PPD is not only as the spacers to prevent aggregating and restacking of the graphene sheets in the preparing process but also as nitrogen sources to obtain the nitrogen-doped graphene.The structures of PPDG were characterized by Fourier transformed infrared spectroscopy(FT-IR),X-ray diffraction spectroscopy(XRD),Raman spectroscopy and X-ray photoelectron spectroscopy(XPS)and the results show that the nitrogen-doped graphene was achieved with nitrogen content as high as 10.85 at.%.The field emission scanning electron microscopy(FE-SEM)and high resolution transmission electron microscopy(HR-TEM)have confirmed that the morphologies of PPDG were loose layered with less aggregation,indicating that PPD molecules,as spacers,effectively prevent the graphene sheets from restacking during the solvothermal reaction.The special loose textures make PPDG materials exhibit excellent electrochemical performance for symmetric SCs with superior specific capacitance(313 F/g at 0.1 A/g),rate capability and cycling stability.The present synthesis method is convenient and may have potential applications as ultrahigh performance SCs.
The development of microwave absorption materials(MAMs) is a considerable important topic because our living space is crowed with electromagnetic wave which threatens human’s health.And MAMs are also used in radar stealth for protecting the weapons from being detected.Many nanomaterials were studied as MAMs,but not all of them have the satisfactory performance.Recently,metal-organic frameworks(MOFs) have attracted tremendous attention owing to their tunable chemical structures,diverse properties,large specific surface area and uniform pore distribution.MOF can transform to porous carbon(PC) which is decorated with metal species at appropriate pyrolysis temperature.However,the loss mechanism of pure MOF-derived PC is often relatively simple.In order to further improve the MA performance,the MOFs coupled with other loss materials are a widely studied method.In this review,we summarize the theories of MA,the progress of different MOF-derived PC-based MAMs,tunable chemical structures incorporated with dielectric loss or magnetic loss materials.The different MA performance and mechanisms are discussed in detail.Finally,the shortcomings,challenges and perspectives of MOF-derived PC-based MAMs are also presented.We hope this review could provide a new insight to design and fabricate MOF-derived PC-based MAMs with better fundamental understanding and practical application.
Electromagnetic interference(EMI)shielding at Terahertz(THz)frequency range attracts increasing attention due to the rapid development of THz science and technologies.EMI shielding materials with small thickness,high shielding effectiveness(SE),good flexibility and stability are highly desirable.Herein,an ultrathin flexible copper/graphene(Cu/Gr)nanolayered composite are prepared,which can reach the average EMI SE of 60.95 dB at 0.1–1.0 THz with a thickness of only 160 nm,indicating that more than 99.9999%of the THz wave power can be shielded.Furthermore,the Cu/Gr nanolayered composite also exhibits excellent oxidation resistance,with a 93.09%maintenance rate for EMI SE value after heating at 120℃for 3 h in air,far higher than that of the bare Cu film(62.15%).Besides,the Cu/Gr nanolayered composite exhibits good mechanical flexibility and flexural fatigue resistance.The EMI SE value of the Cu/Gr nanolayered composite shows a maintenance rate of 98.87%even after 1500 times bending cycles,obviously higher than that of multilayer Cu film(93.07%).These results demonstrate that the ultrathin flexible Cu/Gr nanolayered composites with excellent shielding performance and good stability have a broad application prospect in THz shielding for wearable devices and next generation mobile communication equipment.
Strong chemical interactions between the oxygen-containing functional groups on graphene oxide(GO)sheets and the ions of divalent metals were exploited for the softening of hard water.GO membranes were prepared and evaluated for their ability to absorb Ca2+and Mg2+ions.These GO membranes can effectively absorb Ca2+ions from hard water;a 1 mg GO membrane can remove as much as 0.05 mg Ca2+ions.These GO membranes can be regenerated and used repeatedly.
LIANG JiaJieHUANG YiZHANG FanZHANG YiLI NingCHEN YongSheng
A simple small molecule named DICTiF was designed,synthesized and used as the acceptor for solution processed bulk-heterojunction solar cells with polymer PBDB-T as the donor.A power conversion efficiency of 7.11%was obtained.
A new solution-processable small-molecule donor material, named DRBDT3, comprised of oligobenzo[l,2-b：4,5-b＇] dithio- phene as the backbone and 3-ethyl-rhodanine as the end-capped group has been designed and synthesized for application in organic photovoltaic cells. The oligobenzodithiophene derivative exhibits an absorption band from 300 to 640 nm. The film of DRBDT3 shows highly long-range ordering assembly and high mobility of 1.21×10^-4 cm^2 V^-1 s^-1. The new molecule shows a deep highest-occupied molecular orbital energy level. The device based on DRBDT3 as the donor and PC71BM as the acceptor exhibits a power conversion efficiency of 4.09% with a high open-circuit voltage of 0.99 V under AM. 1.5G illumination （100 mW cm^-2）.
Wang NiMiaomiao LiXiangjian WanYi ZuoBin KanHuanran FengQian ZhangYongsheng Chen
Microwave-absorbing polymeric composites based on single-walled carbon nanotubes （SWNTs） are fabricated via a simple yet versatile method, and these SWNT-epoxy composites exhibit very impressive microwave absorption perfor- mances in a range of 2 GHz-18 GHz. For instance, a maximum absorbing value as high as 28 dB can be achieved for each of these SWNT-epoxy composites （1.3-mm thickness） with only 1 wt% loading of SWNTs, and about 4.8 GHz bandwidth, corresponding to a microwave absorption performance higher than 10 dB, is obtained. Furthermore, such low and appro- priate loadings of SWNTs also enhance the mechanical strength of the composite. It is suggested that these remarkable results are mainly attributable to the excellent intrinsic properties of SWNTs and their homogeneous dispersion state in the polymer matrix.
